Protonation of Borylated Carboxonium Derivative [2,6-B 10 H 8 O 2 CCH 3 ] - : Theoretical and Experimental Investigation.

The process of protonation of [2,6-B 10 H 8 O 2 CCH 3 ] - was investigated both theoretically and experimentally. The most suitable conditions for protonation of the derivative [2,6-B 10 H 8 O 2 CCH 3 ] - were found. The process of protonation was carried out in the presence of an excess of trifluoromethanesulfonic acid CF 3 SO 3 H at room temperature in dichloromethane solution. The structure of the resulting complex [2,6-B 10 H 8 O 2 CCH 3 *H fac ] 0 was established using NMR data and the results of DFT calculations. An additional proton atom H fac was found to be localized on one of the facets that was opposite the boron atom in a substituted position, and which bonded mainly with one apical boron atom. The main descriptors of the B-H fac bond were established theoretically using QTAIM and NBO approaches. In addition, the mechanism of [2,6-B 10 H 8 O 2 CCH 3 ] - protonation was investigated.